Subsea equipment associated with the production of oil and gas is generally designed with a design life of up to about thirty years. Naturally however, faults and failures still regularly occur within these complex pieces of equipment. Intervention operations to recover failed modules may be extremely costly and the availability of vessels to perform these operations at short notice may be limited. Also, failures within the equipment can be potentially harmful to both the environment and personnel safety.
Types of subsea equipment failure include for example:                breakdown of resistance in electrical conductors' insulation and/or breakdown of the conductors themselves;        leaks within hydraulic and chemical systems;        wear within choke valves;        wear within valve actuators; and        failure of controlling electronics.        
A current approach towards detecting such failures is to utilise sensors fitted to subsea equipment to measure various parameters within the electrical/electronic, hydraulic, chemical and production systems. There may be many such sensors deployed subsea. Many of these measurements are monitored via a control system located topside, i.e. at the surface either on land or on a vessel or platform. Currently, parameter monitoring uses statically defined alarm set-points to alert an operator, local to the control system, that an abnormal condition, indicating a fault or failure, is present. By way of simple example, the monitoring system may be set to raise an alarm once a pressure sensor measures a pressure higher than a set, predetermined value. This method has various associated problems. These include:                1. The operators, although familiar with a system's operation, may not be experts in the equipment's behaviour. Consequently, this may affect the reaction time to a problem, as, once an abnormal condition has been detected, the operator may have to contact the supplier of the equipment. This in turn may greatly increase the resolution time and diagnosis of the problem.        2. Due to the nature of statically alarming at low or high set points, the fault condition concerned is often already well-developed by this stage. Therefore scheduling of maintenance, prior to failure of the equipment, may not be feasible.        3. The measurement system does not consider the interaction between components within the fluid production system.        4. The measurement system generally produces a large amount of telemetry data, making it difficult for the operator to understand the health of the system, as some equipment operation is more important than others.        5. Visibility of the status of the system is limited to trained operators and may not be available to a high level user.        